Work. Pt. - Sine wave - Motor - U f N

1. Positioning and objective

The aim of the test “Working point – Sine wave – Motor – U, f, N” is to characterize the behavior of the machine when operating at the targeted input values U, f, N (Magnitude of line-line voltage, Power supply frequency, Speed).

These three inputs are enough to impose a precise working point.

For instance, a working point can be chosen on a torque slip curve, by identifying the voltage, the power supply frequency and the speed with different curves displayed in the “Performance mapping / Sine wave / Motor / T-S” test. Then, the “Working point – Sine wave – Motor – U, f, N” test allows to compute the motor performance for this chosen working point.

“Working point – Sine wave – Motor – U, f, N” Illustration

The results of this test give an overview of the electromagnetic analysis of the machine considering its topology.

The general data of the machine, like mechanical torque, current, power factor, efficiency and power balance are computed and displayed. The motor convention is used to build the model.

The magnetic flux density is also computed in every region of the machine’s magnetic circuit to evaluate the design.

Two computation modes are available:

• “Fast computation mode” is perfectly suited for the pre-design step (Hybrid model based on AC finite element computations and symmetrical component transformation)
• “Accurate computation mode” is perfectly suited for the final design step (Pure Finite Element modeling based on transient computations)

It also gives the capability to make comparisons between the results obtained from measurements and those evaluated with other solution like finite element software.

When both the following conditions are met, this test allows to perform electromagnetic computations with coupled thermal analysis.

• The type of machine is Induction Machines with Squirrel cage with Inner rotor
• One of the two following thermal solving modes is selected: One iteration or iterative solving mode

It also gives the capability to make comparisons between the results got from measurements and those got with our software .

The following table helps to classify the test “Working point – Sine wave – Motor – U, f, N”.

2. User inputs

The four main user input parameters are the supply Line-Line voltage, power supply frequency, speed (or the slip) and the computation mode. In addition, temperatures of winding and squirrel cage must be set.

3. Main outputs

Test results are illustrated with data, graphs, and tables.

3.1 Main results

1. Machine performance – Working point

   • General data
   • Machine constants
   • Power balance
   • Flux in airgap
   • Flux density in iron

2. Power electronics

   • Inverter
   • Working point

3. Thermal data

   • Table of temperatures

3.2 Curves – in the “Fast computation modes”

1. Ripple mechanical torque versus rotor angular position
2. Flux density in airgap versus rotor angular position

3.3 Curves – in the “Accurate computation modes”

1. Mechanical torque versus rotor angular position
2. Mechanical torque harmonic analysis
3. Flux density in airgap versus rotor angular position
4. Flux density in airgap harmonic analysis
5. Phase voltage versus rotor angular position
6. Phase voltage harmonic analysis
7. Phase current versus rotor angular position
8. Phase current harmonic analysis

3.4 Graphics

1. Isovalues

3.5 Temperatures

1. Chart of temperature (radial and axial views)

2. Thermal data

   • Table of temperatures